Russia criticized the U.S. decision to pull out of the Anti-Ballistic Missile treaty, but President Vladimir Putin also said it poses no threat to Russia. China is another matter. Beijing strongly opposed the U.S. decision to scrap the ABM treaty, and some fear the move could lead to a new arms race across Asia.

In the end, the United States and Russia just could not agree on a new strategic framework that would allow the Bush administration to pursue development of a missile defense system, without breaking its obligations under the 1972 ABM treaty.

But the White House is not expecting relations with Moscow to take a tumble as a result of the U.S. decision to withdraw from the accord. Defense analyst Paul Beaver suspects both countries have already agreed to set aside their differences, and will work to improve cooperation on arms control, NATO expansion and fighting terrorism. "I get the impression that a deal was done between President Bush and President Putin last month in Texas," he says. "I think they've agreed that the Russians will not stand in the way of America abrogating of the ABM treaty. It is after all, an out of date treaty."

Now, much of the focus is on how China will respond. China is worried that the Bush administration's planned anti-missile system could nullify its strategic missile force. Western experts say China currently has about 20 long-range nuclear missiles. China also fears a U.S. missile defense could one day be extended to protect its arch-rival, Taiwan.

Michael Levi is a physicist at the Federation of Concerned Scientists, an organization whose members strongly oppose abandoning the ABM treaty and U.S. plans for a missile defense. "It wouldn't be surprising at all if China builds up its arsenal in response," he says. "Now, with a missile defense system in place, China would be inclined to add more warheads, and that would be the upward trend that would instigate an arms race."

China says it remains committed to arms control, but Beijing has already increased defense spending sharply and had warned the U.S. move could lead to an increase in its nuclear arsenal as well. "Now, if China builds up its arsenal, its main regional adversary is India. India may react," he says. "And as a consequence, Pakistan may react, and even if relations warm with China in the future, the damage would already be done."

The Bush Administration is sending a team of senior officials to China next week to explain the U.S. decision. Secretary of State Colin Powell says U.S. plans for missile defense pose no threat to China's security. "I hope they will come to the same conclusion that the Russians came to, that this action is not intended against them," he says. "it is not a threat against their strategic deterrence."

Half of the missile defense-related tests conducted by the Pentagon so far have failed, and it is far from certain whether the technology required to build an effective national missile shield will ultimately work.

But defense analyst Paul Beaver says that might be beside the point. "I think what does concern me more is whether or not other countries will use it as an excuse," he says. "I think that everything has changed since the events of September. And so, therefore, I think that all of that old arms race, cold war rhetoric is dead, and I think it's going to take a very strange politician to try to put it back into place again."

A reference to what he considers the demise of Cold War deterrence, and, given the events of September 11, what could be an entirely different kind of threat, which the ABM treaty was never designed to prevent.